1. Field of the Invention
This invention relates generally to prosthetic devices and more particularly to an improved prosthetic device of the class which are operable to support the user of the device in both sitting and standing positions.
2. Prior Art
Handicapped persons frequently suffer from depression which may be quite severe when the handicap is particularly debilitating or is acquired relatively suddenly as a result of an accident or illness. Paraplegia and quadraplegia are examples of the severe handicaps. In most cases such depression is due not only to the physical and psychological stress which the handicap itself exerts on the body of a handicapped person but also to the loss of independence and earning power which he experiences as a result of the handicap. Accordingly, one way of alleviating the depression of many handicapped persons is to restore to the extent possible their independence and employment capability.
A wide variety of prosthetic devices have been devised for enabling handicapped persons to perform functions which they could not otherwise perform and thereby restoring to some extent their independence and employment capabilities. One such prosthetic device which is particularly beneficial to persons suffering from paralysis of at least the lower body, such as paralegics and quadraplegics, is a wheel chair. A conventional wheel chair, as its name implies, is essentially a chair which is mounted on wheels for movement from one location to another and is designed to support the user in a sitting position. Some wheel chairs are motorized and equipped with controls which the user may operate to drive and steer such wheel chairs.
Conventional wheel chairs, then, are quite satisfactory for use in those situations in which a sitting position is comfortable and appropriate. Such a sitting position, however, is not always the most comfortable or appropriate. For example, prolonged orientation of a person in a sitting position can become quite uncomfortable, and the comfort of a wheel chair user can be significantly enhanced by enabling the user to periodically assume an upright standing position. Moreover, most people can converse with another person or persons with the greatest ease and least emotional stress when they don't have to look up or down at the other persons. In the case of a handicapped person seated in a conventional wheel chair, this condition exists only if other persons seated and hence would often not exist in many social and other situations where it is impossible or inappropriate for non-handicapped persons to sit. Accordingly, it would be highly desireable for a wheel-chair-bound person to be able to assume a standing position in such situations. Another situation in which it is often highly desireable, if not absolutely essential, for a handicapped person in a wheel chair to assume a standing position is in a work environment where the work task assigned to the person can be performed most effectively or only in a standing position.
For the reasons just stated, prosthetic devices commonly referred to as wheel chairs have been devised which enable the handicapped user to assume both sitting and standing positions. Examples of such "sit/stand" prosthetic devices or wheel chairs are described in U.S. Pat. Nos. 4,054,319, 4,456,086, and 4,809,804. While these and other similar sit/stand prosthetic devices or wheel chairs are capable of performing their intended functions, they have certain deficiencies which this invention overcomes. Among the foremost of these deficiencies are the following: an excessive number of parts and resulting excessive complexity and relatively high cost of manufacture; excessive overall size and weight; lack of means for effectively aiding the handicapped user to assume standing and sitting positions by physically but gently lifting and lowering the handicapped user to these positions; inability to quickly and easily dissassemble or collapse the devices for ease of storage and transportation. Accordingly, there is a definite need for an improved sit/stand prosthetic device or wheel chair.